At least 23 people have been killed and dozens injured after thunderstorms and tornadoes ripped across Mississippi leaving hundreds without shelter, state officials say.

Four people were missing following the storms, which left a trail of damage for more than 160 kilometres.

The tornadoes struck Silver City, a town of 200 people in western Mississippi, as well as Rolling Fork, with a population of 1700, which was hardest hit.

Parts of the state remain under tornado warning.

“At least 23 Mississippians were killed by last night’s violent tornadoes,” Mississippi Governor Tate Reeves wrote on Twitter.

“We know that many more are injured. Search and rescue teams are still active. The loss will be felt in these towns forever.”

Reeves declared a state of emergency in the affected areas, which he said would remain in effect “until such time as this threat to public safety shall cease to exist”.

US President Joe Biden described the images from Mississippi as “heartbreaking” and said in a statement that he had spoken with Reeves and offered his condolences and full federal support for the recovery.

“To those impacted by these devastating storms, and to the first responders and emergency personnel working to help their fellow Americans, we will do everything we can to help,” Biden said.

“We will be there as long as it takes. We will work together to deliver the support you need to recover.”

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Federal Emergency Management Agency) director Deanne Criswell told CNN that she would travel to Mississippi on Sunday.

Ms Criswell pledged to process quickly an anticipated request from Mississippi for a major disaster declaration to enable full federal support now and over the long term.

FEMA was already on the ground, she said, adding that the American Red Cross was setting up shelters.

Search and rescue teams combed through the destruction looking for survivors in Silver City and Rolling Fork.

“My city is gone but we are resilient,” Rolling Fork Mayor Eldridge Walker said on CNN.

“We are going to come back strong.”

Mr Walker said several people were trapped in their homes, adding that rescue efforts were underway.

He said 12 of the people who died were in Rolling Fork.

Television images showed uprooted trees, houses ripped apart and damaged motor vehicles.

Many areas were without electricity.

Humphreys County Sheriff Bruce Williams told CNN that “this town has been destroyed like a bomb hit it”.

Mr Williams said no missing persons had been reported but three deaths had been confirmed in the county.

– AAP